This project is designed to study the mechanisms by which narcotics depress ventilation. Narcotics will be administered iontophoretically and the responses of respiratory neurons to this localized administration of the drugs will be described. Similar investigations will examine the responses of respiratory neurons to the iontophoretic administration of endorphins. The respiratory neurons are located in discrete regions of the brainstem and it will be ascertained whether the neurons in these regions respond in a similar manner to locally administered narcotics.